In recent years, compression technology is developed, and video data, etc. have been also compressed by, e.g., DV (Digital Video) system so that data thus compressed are recorded onto a magnetic tape. Format therefor is prescribed as DV format of consumer digital video tape recorders.
FIG. 1 shows the configuration of one track of a conventional DV format. In the DV format, video data are recorded after they have been 24-25 converted. In this case, the numbers of bits of figures shown in FIG. 1 represent numeric values after 24-25 conversion has been performed.
The range corresponding to winding angle of 174 degrees of magnetic tape is caused to be range of substantial one track. At the outside of the range of one track, overwrite margin having length of 1250 bits is formed. The overwrite margin serves to eliminate erasing remainder of data.
In the case where the rotary head is rotated in synchronism with frequency of 60×1000/1001 Hz (hereinafter referred to as 60 Hz), length of the range of one track is caused to be 134975 bits. In the case where the rotary head is rotated in synchronism with frequency of 50×1000/1001 Hz (hereinafter referred to as 50 Hz), the length of the range of one track is caused to be 134850 bits.
At one track, in the trace direction of the rotary head (from left direction to right direction in FIG. 1), ITI (Insert and Track Information) sector, audio sector, video sector and Subcode sector are arranged (assigned) in succession. Between the ITI sector and the audio sector, gap G1 is formed. Between the audio sector and the video sector, gap G2 is formed. In addition, between the video sector and the Subcode sector, gap G3 is formed.
The ITI sector is caused to have length of 3600 bits, and preamble of 1400 bits for generating clock is disposed (assigned) at the leading portion thereof. At the portion succeeding thereto, SSA (Start Sync Area) and TIA (Track Information Area) are provided by length corresponding to 1920 bits. At the SSA, bit train (Sync No.) necessary for detecting the position of TIA is disposed (assigned). At the TIA, there are recorded information indicating consumer DV format, information indicating SP recording mode or LP recording mode, and information indicating pattern of pilot signal of one frame, etc. At the portion succeeding to the TIA, postamble of 280 bits is disposed (assigned).
The gap G1 is caused to have length of 625 bits. The audio sector is caused to have length of 11550 bits, and the leading 400 bits and the last 500 bits are caused to be respectively preamble and postamble, wherein 10650 bits therebetween is caused to be data (audio data). The gap G2 is caused to have length of 700 bits.
The video sector is caused to have length of 113225 bits, and the leading 400 bits and the last 925 bits are respectively preamble and postamble, wherein 111900 bits therebetween is caused to be data (video data). The gap G3 is caused to have length of 1550 bits.
When the rotary head is rotated in synchronism with frequency of 60 Hz, the Subcode sector is caused to have length of 3725 bits. When the rotary head is rotated in synchronism with frequency of 50 Hz, the Subcode sector is caused to have length of 3600 bits. The leading 1200 bits thereof is caused to be preamble, and the last 1325 bits (at the time of 60 Hz) or the last 1200 bits (at the time of 50 Hz) is caused to be postamble, wherein 1200 bits therebetween is caused to be data (subcode).
In the DV format, there was the problem that not only gaps G1 to G3 are formed between the ITI sector, the audio sector, the video sector, and the Subcode sector, but also preambles and postambles are provided are provided every respective sectors as stated above so that the so-called overhead is long thus to fail to sufficiently ensure recording rate of substantial data.
As a result, in the case where, e.g., High Definition video data (hereinafter referred to as HD video data) is recorded, bit rate of about 25 Mbps is required. However, in this recording format, only about 24 Mbps is required at the utmost as video rate with respect to MP@HL of the MPEG (Moving Picture Expert Group) except for data for search image. As a result, there was the problem that even if recording of Standard Definition video data (hereinafter referred to as SD video data) can be performed, it is impossible to compress HD video data by the MP@HL system or the MP@H-14 system, etc. to record such compressed video data.
In order to cope with the above-mentioned problem, in the DV format, ATV recording format (Specifications of Consumer-Use Digital VCRs, PART8 (ATV Specifications of Consumer-Use Digital VCR) and Specifications of Consumer-Use Digital VCRs, PART7 (DVB Specifications of Consumer-Use Digital VCR)) is defined in order to record HD video data. However, in the case where the recording format is in conformity with the DV format, only about 18.7 Mbps in total can be recorded as ES (Elementary Stream), and it was therefore necessary to separately define recording format in order to obtain higher picture quality and/or higher sound quality.
Moreover, there is a technology in which in the case where data which is in conformity with the DV format (SD data) and data which is not in conformity with the DV format HD format (HD data) are recorded in a mixed state, values of APT (Application ID of a track) of ITI of SD data and HD data are set to different values in order to recognize respective data. In this case, value of APT of ITI of SD data is value “000” indicating that the recording format is in conformity with the DV format.
However, when value of APT is set to value indicating that the recording format is not in conformity with the DV format (e.g., “010”), recording state would be recognized as Reserved state (unrecognizable recording is performed) in consumer digital video tape recorders which comply with only the DV format, the same behavior as that when non-recorded tape reproduced is performed with respect to user may be performed. As a result, there is the problem that previously recorded data might be erroneously erased, or might be overwrite-recorded by other data.